1. Field of the Invention
The present invention relates to a musical tone signal generating apparatus having a tone generator including tone generation channels for generating musical tone signals, the musical tone signal generating apparatus assigning generation of new one or more musical tone signals to one or more of the tone generation channels to generate a musical tone in accordance with the one or more musical tone signals.
2. Description of the Related Art
There have been conventional musical tone signal generating apparatuses having a CPU which instructs the start of generation of a musical tone signal and a tone generator which starts the generation of the musical tone signal in response to the instruction, as disclosed in Japanese Unexamined Patent Publication No. 2005-107029, for example. The tone generator of this conventional musical tone signal generating apparatus has a plurality of tone generation channels for generating musical tone signals. In the conventional musical tone signal generating apparatus, in a case where the CPU instructs the tone generator to newly start generation of a different musical tone signal in spite of all the tone generation channels being currently generating musical tone signals, respectively, the CPU selects one of the tone generation channels to instruct decay of the tone volume level of the musical tone signal currently generated in the selected tone generation channel. The CPU then keeps monitoring the tone volume level of the musical tone signal output from the tone generation channel to which the CPU has instructed to decay the tone volume level. When the monitored tone volume level of the musical tone signal attains a certain small level (hereafter referred to as a damp level), the CPU instructs to start generating the different musical tone signal.
Furthermore, in accordance with an instruction to generate a musical tone signal made by manual musical performance played by a player on a keyboard or an instruction to generate a musical tone signal made by automatic musical performance played by reading out performance information previously stored in a memory, the conventional musical tone signal generating apparatus assigns the generation of the musical tone signal to one or more tone generation channels. As soon as the tone volume level of a musical tone signal currently generated in the tone generation channel decays to be a certain threshold level (a damp level) or less, the tone generation channel becomes vacant to be available for a new depression of a key to be ready to newly generate a musical tone signal.